Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
cham tuc » nham thuc, tham thuc, cham soc
hanh doi » thanh doi, hanh noi, hang doi
cau tren » cu tren, dau tren, ca tren
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va thanh, va danh
doi cau » doi dau, di cau, doi ca
5 hoi » o hoi

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((5 hoi) OR (x ho)). hieu qua ((cham tuc) OR (pham thuc)) va hanh doi cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((5 hoi) or (x ho)). hieu qua ((cham tuc) OR (pham thuc)) va hanh doi cau tren~".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((5 hoi) or (x ho)). hieu qua ((cham tuc) OR (pham thuc)) va hanh doi cau tren*.